> [John Hazen] > > I want to match one or two instances of a pattern in a string. > > > > >>> s = 'foobarbazfoobar' > > >>> foofoo = re.compile(r'^(foo)(.*?)(foo)?(.*?)$') > > >>> foofoo.match(s).group(1) > > 'foo' > > >>> foofoo.match(s).group(3) > > >>>
[Tim Peters] > Your problem isn't that > > (foo)? > > is not greedy (it is greedy), it's that your first > > (.*?) > > is not greedy. Remember that regexps also work left to right. Well, I had the same symptoms when that .* was greedy (it ate up the optional foo), which is why I went to non-greedy there. I guess my error was thinking that greedy trumped non-greedy, rather than left trumping right. (ie, in order for the (foo)? to be maximally greedy, the (.*?) has to be non-maximally non-greedy :) > Maybe what you're looking for is > > ^P(.*P)?.*$ Yes. That works the way I wanted. ( ^(foo)(.*(foo))?.*$ ) Thank you, both for the specific answer, and the general education. -John -- http://mail.python.org/mailman/listinfo/python-list
